Accuracy evaluation of a calculation tool based on the spectral colour property of indoor luminous environments

The circadian rhythms of building occupants are affected by the brightness and spectral colour property of the indoor luminous environment. The spectral colour property of the indoor luminous environment is determined by the spectral power distribution (SPD) of the luminaire light and light reflected by the interior finish. However, conventional lighting simulation programmes cannot calculate the spectral colour property of light reflected from the interior finish; thus, the influence of the indoor luminous environment on the circadian rhythms of occupants cannot be determined. Therefore, a Spectral Colour Property Assessment Tool (SCPAT) that utilises the spectral reflectance of indoor materials and SPD data of luminaires was previously developed by our research group. The accuracy of the SCPAT developed in our previous study was evaluated by studying the illuminance value of a conventional lighting simulation programme; however, the spectral colour property accuracy cannot be evaluated using the conventional lighting simulation programme. Accordingly, this study evaluated the accuracy of SCPAT by comparing the measured spectral colour property values in a full-scale mock-up with spectral colour property values calculated using SCPAT. The accuracy evaluation indicated that the average error ratio of the mean illuminance was within 2.5%; the average error ratio of the correlated colour temperature (CCT) was approximately 1.11%; and the average error ratios of the CCT, SPD and CAF of the light incident upon the field of view of occupants were 0.11%, 0.11% and 0.04%, respectively.